Calibration circuit including common node shared by pull-up calibration path and pull-down calibration path, and semiconductor memory device including the same

摘要

A calibration circuit includes first and second pull-up units each receiving a pull-up code and connected between a pad connected with an external resistor and a first power supply voltage, a pull-down unit connected between the pad and a second power supply voltage and receiving a pull-down code, a comparator comparing a first voltage with a reference voltage and then compare a second voltage with the reference voltage, a first digital filter adjusting the pull-up code based on a first comparison result of the first voltage with the reference voltage, and a second digital filter adjusting the pull-down code based on a second comparison result of the second voltage with the reference voltage.